Refactor filter_events_for_server (#15240)

* Tweak docstring and type hint

* Flip logic and provide better name

* Separate decision from action

* Track a set of strings, not EventBases

* Require explicit boolean options from callers

* Add explicit option for partial state rooms

* Changelog

* Rename param
This commit is contained in:
David Robertson 2023-03-10 15:31:25 +00:00 committed by GitHub
parent e157c63f68
commit 4bb26c95a9
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5 changed files with 109 additions and 30 deletions

1
changelog.d/15240.misc Normal file
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@ -0,0 +1 @@
Refactor `filter_events_for_server`.

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@ -547,6 +547,8 @@ class PerDestinationQueue:
self._server_name,
new_pdus,
redact=False,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
# If we've filtered out all the extremities, fall back to

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@ -392,7 +392,7 @@ class FederationHandler:
get_prev_content=False,
)
# We set `check_history_visibility_only` as we might otherwise get false
# We unset `filter_out_erased_senders` as we might otherwise get false
# positives from users having been erased.
filtered_extremities = await filter_events_for_server(
self._storage_controllers,
@ -400,7 +400,8 @@ class FederationHandler:
self.server_name,
events_to_check,
redact=False,
check_history_visibility_only=True,
filter_out_erased_senders=False,
filter_out_remote_partial_state_events=False,
)
if filtered_extremities:
extremities_to_request.append(bp.event_id)
@ -1331,7 +1332,13 @@ class FederationHandler:
)
events = await filter_events_for_server(
self._storage_controllers, origin, self.server_name, events
self._storage_controllers,
origin,
self.server_name,
events,
redact=True,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
return events
@ -1362,7 +1369,13 @@ class FederationHandler:
await self._event_auth_handler.assert_host_in_room(event.room_id, origin)
events = await filter_events_for_server(
self._storage_controllers, origin, self.server_name, [event]
self._storage_controllers,
origin,
self.server_name,
[event],
redact=True,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
event = events[0]
return event
@ -1390,7 +1403,13 @@ class FederationHandler:
)
missing_events = await filter_events_for_server(
self._storage_controllers, origin, self.server_name, missing_events
self._storage_controllers,
origin,
self.server_name,
missing_events,
redact=True,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
return missing_events

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@ -14,7 +14,17 @@
# limitations under the License.
import logging
from enum import Enum, auto
from typing import Collection, Dict, FrozenSet, List, Optional, Tuple
from typing import (
Collection,
Dict,
FrozenSet,
List,
Mapping,
Optional,
Sequence,
Set,
Tuple,
)
import attr
from typing_extensions import Final
@ -565,29 +575,43 @@ async def filter_events_for_server(
storage: StorageControllers,
target_server_name: str,
local_server_name: str,
events: List[EventBase],
redact: bool = True,
check_history_visibility_only: bool = False,
events: Sequence[EventBase],
*,
redact: bool,
filter_out_erased_senders: bool,
filter_out_remote_partial_state_events: bool,
) -> List[EventBase]:
"""Filter a list of events based on whether given server is allowed to
"""Filter a list of events based on whether the target server is allowed to
see them.
For a fully stated room, the target server is allowed to see an event E if:
- the state at E has world readable or shared history vis, OR
- the state at E says that the target server is in the room.
For a partially stated room, the target server is allowed to see E if:
- E was created by this homeserver, AND:
- the partial state at E has world readable or shared history vis, OR
- the partial state at E says that the target server is in the room.
TODO: state before or state after?
Args:
storage
server_name
target_server_name
local_server_name
events
redact: Whether to return a redacted version of the event, or
to filter them out entirely.
check_history_visibility_only: Whether to only check the
history visibility, rather than things like if the sender has been
redact: Controls what to do with events which have been filtered out.
If True, include their redacted forms; if False, omit them entirely.
filter_out_erased_senders: If true, also filter out events whose sender has been
erased. This is used e.g. during pagination to decide whether to
backfill or not.
filter_out_remote_partial_state_events: If True, also filter out events in
partial state rooms created by other homeservers.
Returns
The filtered events.
"""
def is_sender_erased(event: EventBase, erased_senders: Dict[str, bool]) -> bool:
def is_sender_erased(event: EventBase, erased_senders: Mapping[str, bool]) -> bool:
if erased_senders and erased_senders[event.sender]:
logger.info("Sender of %s has been erased, redacting", event.event_id)
return True
@ -616,7 +640,7 @@ async def filter_events_for_server(
# server has no users in the room: redact
return False
if not check_history_visibility_only:
if filter_out_erased_senders:
erased_senders = await storage.main.are_users_erased(e.sender for e in events)
else:
# We don't want to check whether users are erased, which is equivalent
@ -631,15 +655,15 @@ async def filter_events_for_server(
# otherwise a room could be fully joined after we retrieve those, which would then bypass
# this check but would base the filtering on an outdated view of the membership events.
partial_state_invisible_events = set()
if not check_history_visibility_only:
partial_state_invisible_event_ids: Set[str] = set()
if filter_out_remote_partial_state_events:
for e in events:
sender_domain = get_domain_from_id(e.sender)
if (
sender_domain != local_server_name
and await storage.main.is_partial_state_room(e.room_id)
):
partial_state_invisible_events.add(e)
partial_state_invisible_event_ids.add(e.event_id)
# Let's check to see if all the events have a history visibility
# of "shared" or "world_readable". If that's the case then we don't
@ -658,17 +682,20 @@ async def filter_events_for_server(
target_server_name,
)
to_return = []
for e in events:
def include_event_in_output(e: EventBase) -> bool:
erased = is_sender_erased(e, erased_senders)
visible = check_event_is_visible(
event_to_history_vis[e.event_id], event_to_memberships.get(e.event_id, {})
)
if e in partial_state_invisible_events:
if e.event_id in partial_state_invisible_event_ids:
visible = False
if visible and not erased:
return visible and not erased
to_return = []
for e in events:
if include_event_in_output(e):
to_return.append(e)
elif redact:
to_return.append(prune_event(e))

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@ -63,7 +63,13 @@ class FilterEventsForServerTestCase(unittest.HomeserverTestCase):
filtered = self.get_success(
filter_events_for_server(
self._storage_controllers, "test_server", "hs", events_to_filter
self._storage_controllers,
"test_server",
"hs",
events_to_filter,
redact=True,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
)
@ -85,7 +91,13 @@ class FilterEventsForServerTestCase(unittest.HomeserverTestCase):
self.assertEqual(
self.get_success(
filter_events_for_server(
self._storage_controllers, "remote_hs", "hs", [outlier]
self._storage_controllers,
"remote_hs",
"hs",
[outlier],
redact=True,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
),
[outlier],
@ -96,7 +108,13 @@ class FilterEventsForServerTestCase(unittest.HomeserverTestCase):
filtered = self.get_success(
filter_events_for_server(
self._storage_controllers, "remote_hs", "local_hs", [outlier, evt]
self._storage_controllers,
"remote_hs",
"local_hs",
[outlier, evt],
redact=True,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
)
self.assertEqual(len(filtered), 2, f"expected 2 results, got: {filtered}")
@ -108,7 +126,13 @@ class FilterEventsForServerTestCase(unittest.HomeserverTestCase):
# be redacted)
filtered = self.get_success(
filter_events_for_server(
self._storage_controllers, "other_server", "local_hs", [outlier, evt]
self._storage_controllers,
"other_server",
"local_hs",
[outlier, evt],
redact=True,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
)
self.assertEqual(filtered[0], outlier)
@ -143,7 +167,13 @@ class FilterEventsForServerTestCase(unittest.HomeserverTestCase):
# ... and the filtering happens.
filtered = self.get_success(
filter_events_for_server(
self._storage_controllers, "test_server", "local_hs", events_to_filter
self._storage_controllers,
"test_server",
"local_hs",
events_to_filter,
redact=True,
filter_out_erased_senders=True,
filter_out_remote_partial_state_events=True,
)
)